Welcome to Flashoholics Anonymous, shackleton!
Has anyone changed better driver into this flashlight to get more light from it?
When I make deep dives, I need as much light as possible, but those deep dives are not very long. 1 hour runtime would be enough at full power. Also it would be nice to have lower power modes for longer dives.
So what is happening here? Is it the salt water dissolving the aluminum?
No. It's not a problem of salt, but the salt partecipate to what is happening.
What you see there is typical electrical corrosion happening underwater: electrolysis. I work with ships, and know well enough the problem.
When this light is switched on, the ground (or -B as you prefer to call it) is from the cell bottom to the tailcap, and tailcap fully tightened makes contact with body, so also body is grounded, the ground then goes to driver and led. The + pole from cell goes to driver and led. The circuit is closed and the light is on. There's no difference of electrical potential between body and tailcap and no corrosion happens.
But when the light is off, the ground is only the tailcap. Not being fully tightened means no contact with body, so body is not grounded. So what happens next? Happens that + pole goes through driver and led, and to body. The circuit is open between tailcap and body. That is easy to figure out, anything that can electrically connect body and tail, will let current flow, and light will switch on. Well, when the light is on air, the air is relatively dry and a very bad conductor, so no problem. But when immersed in seawater, the salt rich seawater act as an electrolyte, and happily flows electrons. The body and tailcap are acting as anode and cathode, the cells supply the power, the seawater is the perfect electrolyte to the job: the anode release electrons and the electron-deprived metal corrode and dissolutes in the water (pitting), the cathode receives the electrons and in the area builds up a layer of whitish minerals from the water.
As soon as the cell can supply current, the corrosion will not stop, untill the cells are depleted or all the metal dissolved. The higher the current rate the cells can supply, the faster the corrosion. The anodization prevents the aluminium from corroding in air atmosphere (anodization is an induced passivation, which is electrically inert in air), but can nothing when in seawater, because the chlorides (salt) dissolve the alu oxides forming the anodization.
The next bad part of the figure is that there's no real solution to this. The use of a mechanical or magnetic switch (rubber booted) and keeping body and tailcap grounded (electrically connected) will anyway slow the corrosion rate by an enormous margin, eliminating the current dispersion.
Note anyway that alu in seawater will corrode, and any scratch to the anod is a good starting point.
Note also that most frequently used alu "light alloys" are not suited for seawater immersion, because of copper content. The alu alloys for marine service are special alloys low on copper and high on magnesium and manganese. Can you bet, they are more expensive than other "normal" alloys for terrestrial application, so I can hardly believe a flashlight producer will invest in these. Much easier to use PVC or other high tech "plastic".
Hey Rockspider,
Wouldn’t it be possible to isolate the grounding from the bottom of the batteries, and connect it through a wire to the circuit board? Maybe there is not enough space inside the body for the wire, but maybe some kind of isolated flat wire?
I agree that using aluminum is a problem in itself. That’s why you don’t see many genuine diving torches in this material.
I know it is off topic, but the Danish company Wiseled makes some high quality underwater flashlights, who apparently have solved all these problems. The reason being off topic is, that they are unhealthy expensive: http://www.wiseled.com/flashlight_adventure_diving.htm
Peter
Thanks rockspider for the great explanation!!… RE: electrolysis and electrical potential.
thanks!!
Re: Olderman
Yes making an internal wire connection between battery minus and driver would solve the different potential issue between body and tailcap, but anyway the tailcap must always be well tight in order to keep the same potential as body.
Re: Kramer
Thanks
I know that this torch is not sold by DX alone, but they are one of the big resellers, and they are official members of this forum.
What is their explanation of this Trustfire TR DF003 having those big issues? Maybe they should ask the company Trustfire or whoever is behind the design of it.
All we see is an ‘ooops we just correct the lumen output in the spec’s’, nothing else. Maybe I just haven’t read the official statement, but there should in my mind be some kind of statement from the supplier / producer after this kind of blunder.
Are you all satisfied with your money back, and that’s it? Wouldn’t it be fair to ask for an explanation? Wouldn’t it be nice to hear, what they are going to do in the future? Are there going to be an updated version with all problems solved?
Am I too demanding? :~
Just got this light and took it to a dive in dark water. The beam seems to be too scattered for these murky waters but I’m still going to try modding it. Ordered a new driver for it that should give 3 A of current and also a switch and a rubber boot for it. I’m going to install the switch to the tailcap and it will still use the body of the light for connection but the switch will cut the minus from it when turned off. So electrolysis and switching modes should not be a problem
We’ll see if I can make it waterproof and boosted up…
Ok, I just ordered one of these torches online and I am now reading all of this bad news about them. (FML)
I guess that is why the trustfire website doesn’t even have them on their website and removed them from Amazon.
Anyway, I have no choice but to try to modify it and give it a go. First on the list are new O-rings. I will probably just buy viton o-rings. Can someone please tell me the two different sizes?
O-ring lubricant, I will opt for aqualube or molykote-111.
I need to know how to put in a tail cap to stop the corrosion on these lights. Whoever figures this out please share some pics!!
I agree. They might as well slap some black paint on the front of the lens while they are at it. Proof that the people in the design dept work on a different planet than the ones that do the actual testing.
I just took off the reflectors off mine. Even though the LED’s are 2 inches in past the bezel it still gives a nice wide beam… Not very bright at all but 2 are good enough for my GoPro set up which is why I need to find a way to fix the corrosion issue.
All these diving lights are moderately driven so they run longer on a dive. With the Trustfire cells provided in the kit, I get exactly 2a at the tailcap. And yes, it does give a nice beam even though the reflector is set back very far.
Hi 300winmag,
Have you thought about galvanizing and sealing your torch?
Alternatively, take it to your nearest anodizer and get them to anodize it.
I am still waiting for my torch to arrive so I can examine it. Pretty much, you have to turn it on before you dive? Otherwise the water passes the seals and it short circuits. What a flawed design.
I also disassembled my torch and figured out that the leds are connected in parallel. So as the tailcap amps are a bit over 2 A, isn’t the A per led something like 0.77?
I allready connected them in series and switched the driver for it and it seems a lot brighter. I also fixed the switch problem adding a push button switch to the tailcap that isolates the minus potential from the body when not turned on. Should fix the corroding problem. Still have to figure out, how to make it 100 % waterproof.
Altough I have some bigger plans for this lamp since it’s inner design seems to be a LOT better than the overall with this tailcap and using only two cells…
I can post more and some photos later
Would anodizing get rid of this corrosion problem?
Yes you have to turn it on before you enter the water and no other modes while in the water either.
Please post pics and links to where you got your parts from
Here’s some pictures of the disassembled lamp: dropbox gallery
I’m planning to use only the lighthead of the lamp with a canister. Also most propably replacing the XML’s with sst-90’s. ATM trying to find out if you can make the bigger led’s fit with the reflector and heatsink. Propably going to use this driver with that triple sst-90
No idea, I don’t have the torch yet to conduct tests. It’s already anodized so maybe they can put a thicker/harder layer on. I’ll be trying out Pokasha’s trick first by replacing the LED driver and soldering them in series. Definitely changing the o-rings and applying aqua shield. I won’t be functioning the torch underwater. Turning it ON before entering and leaving it ON.
Won’t delve into adding a push button/switch. I fear the torch would lose it’s water depth rating and render itself useless. I also don’t see any point in engineering a new longer tail cap with a longer seal face. I would much rather spend the extra money and buy a XTAR D35 or similar as a backup.